1 /*
2 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9 #include <linux/types.h>
10 #include <linux/sctp.h>
11 #include <net/sctp/checksum.h>
12
13 #include <net/netfilter/nf_nat_l4proto.h>
14
15 static u_int16_t nf_sctp_port_rover;
16
17 static void
sctp_unique_tuple(const struct nf_nat_l3proto * l3proto,struct nf_conntrack_tuple * tuple,const struct nf_nat_range * range,enum nf_nat_manip_type maniptype,const struct nf_conn * ct)18 sctp_unique_tuple(const struct nf_nat_l3proto *l3proto,
19 struct nf_conntrack_tuple *tuple,
20 const struct nf_nat_range *range,
21 enum nf_nat_manip_type maniptype,
22 const struct nf_conn *ct)
23 {
24 nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
25 &nf_sctp_port_rover);
26 }
27
28 static bool
sctp_manip_pkt(struct sk_buff * skb,const struct nf_nat_l3proto * l3proto,unsigned int iphdroff,unsigned int hdroff,const struct nf_conntrack_tuple * tuple,enum nf_nat_manip_type maniptype)29 sctp_manip_pkt(struct sk_buff *skb,
30 const struct nf_nat_l3proto *l3proto,
31 unsigned int iphdroff, unsigned int hdroff,
32 const struct nf_conntrack_tuple *tuple,
33 enum nf_nat_manip_type maniptype)
34 {
35 struct sctphdr *hdr;
36 int hdrsize = 8;
37
38 /* This could be an inner header returned in imcp packet; in such
39 * cases we cannot update the checksum field since it is outside
40 * of the 8 bytes of transport layer headers we are guaranteed.
41 */
42 if (skb->len >= hdroff + sizeof(*hdr))
43 hdrsize = sizeof(*hdr);
44
45 if (!skb_make_writable(skb, hdroff + hdrsize))
46 return false;
47
48 hdr = (struct sctphdr *)(skb->data + hdroff);
49
50 if (maniptype == NF_NAT_MANIP_SRC) {
51 /* Get rid of src port */
52 hdr->source = tuple->src.u.sctp.port;
53 } else {
54 /* Get rid of dst port */
55 hdr->dest = tuple->dst.u.sctp.port;
56 }
57
58 if (hdrsize < sizeof(*hdr))
59 return true;
60
61 if (skb->ip_summed != CHECKSUM_PARTIAL) {
62 hdr->checksum = sctp_compute_cksum(skb, hdroff);
63 skb->ip_summed = CHECKSUM_NONE;
64 }
65
66 return true;
67 }
68
69 const struct nf_nat_l4proto nf_nat_l4proto_sctp = {
70 .l4proto = IPPROTO_SCTP,
71 .manip_pkt = sctp_manip_pkt,
72 .in_range = nf_nat_l4proto_in_range,
73 .unique_tuple = sctp_unique_tuple,
74 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
75 .nlattr_to_range = nf_nat_l4proto_nlattr_to_range,
76 #endif
77 };
78